Most consumers have come to expect scented laundry products and to expect that fabrics which have been laundered also to have a pleasing fragrance. Perfume additives make laundry compositions more aesthetically pleasing to the consumer, and in some cases the perfume imparts a pleasant fragrance to fabrics treated therewith. However, the amount of perfume carryover from an aqueous laundry bath onto fabrics is often marginal. The detergent manufacturing industry, therefore, has long searched for an effective perfume delivery system for use in laundry products which provides long-lasting, storage-stable fragrance to the product, as well as fragrance to the laundered fabrics.
Laundry and other fabric care compositions which contain perfume mixed with or sprayed onto the compositions are well known in the art and currently commercialized. Because perfumes are made of a combination of volatile compounds, perfume can be continuously emitted from simple solutions and dry mixes to which the perfume has been added. Various techniques have been developed to hinder or delay the release of perfume from compositions so that they will remain aesthetically pleasing for a longer length of time. To date, however, few of the methods deliver significant fabric odor benefits after prolonged storage of the product.
Moreover, there has been a continuing search for methods and compositions which will effectively and efficiently deliver perfume from laundering solutions onto fabric surfaces. As can be seen from the following disclosures in the prior art, various methods of perfume delivery have been developed involving protection of the perfume through the wash cycle, with release of the perfume onto fabrics. For example, one method entails delivering fabric conditioning agents, including perfume, through the wash and dry cycle via a fatty quaternary ammonium salt. Another method involves a microencapsulation technique which involves the formulation of a shell material which will allow for diffusion of perfume out of the capsule only at certain temperatures. Yet another method involves incorporating perfume into waxy particles to protect the perfume through storage in dry compositions and through the laundry process. The perfume allegedly diffuses through the wax on the fabric in the dryer. Further prior art disclosures involve perfume dispersed with a water-insoluble nonpolymeric carrier material and encapsulated in a protective shell by coating with a water-insoluble friable coating material, and a perfume/cyclodextrin complex protected by clay which provides perfume benefits to at least partially wetted fabrics.
Still another method for delivery of perfume in the wash cycle involves combining the perfume with an emulsifier and water-soluble polymer, forming the mixture into particles, and adding them to a laundry composition. The perfume can also be adsorbed onto a porous carrier material, such as a polymeric material. Perfumes have also been adsorbed onto a clay or zeolite material which is then admixed into particulate detergent compositions. Generally, the preferred zeolites have been Type A or 4A Zeolites with a nominal pore size of approximately 4 Angstrom units. It is now believed that with Zeolite A or 4A, the perfume is adsorbed onto the zeolite surface with relatively little of the perfume actually absorbing into the zeolite pores.
While the adsorption of perfume onto zeolite or polymeric carriers may perhaps provide some improvement over the addition of neat perfume admixed with detergent compositions, industry is still searching for improvements in the length of storage time of the laundry compositions without loss of perfume characteristics, in the intensity or amount of fragrance delivered to fabrics, and in the duration of the perfume scent on the treated fabric surfaces. Furthermore, even with the substantial work done by prior skilled artisans in this area, a need still exists for a simple, more efficient and effective perfume delivery system, preferably in particulate form, which can be mixed with laundry compositions to provide initial and lasting perfume benefits to fabrics which have been treated with the laundry product.
Another problem associated with perfume delivery systems, especially those in particulate form, is concerned with the method by which such particulate perfume delivery systems are made. It has been difficult to produce perfume delivery systems particularly those involving zeolite or polymeric carriers in an economic and efficient manner. Oftentimes, a significant amount of the perfume will evaporate from the carrier material during processing as well as during storage prior to use. Additionally, many materials which are included in the perfume delivery system to prevent the volatilization of perfume prior to deposition on fabrics can degrade during manufacture, thereby losing its effectiveness. Thus, there has been a need for not only an effective perfume delivery system or additive for laundry detergents, but for a process which can produce such a laundry perfume delivery additive which is efficient, economical and minimizes the evaporation of perfume and degradation of materials used to minimize perfume evaporation during processing.
Accordingly, despite the aforementioned disclosures in the art, there remains a need for a process for producing a particulate laundry additive composition for perfume delivery in laundry detergent and other cleaning or fabric softening products. Additionally, there is a need for such a process which is not only more economical and efficient, but also minimizes the evaporation of perfume and the degradation of materials used in this regard during production.